BACKGROUND Diagnosis and management of ACO (the anatomic substrate for ST-elevation myocardial infarction) is time sensitive. Diagnosis necessitates emergent reperfusion therapy. An important predictor of death from ACO includes time to reperfusion.1 Delays in reperfusion therapy, including primary percutaneous coronary intervention (PCI) or fibrinolysis, are associated with worse 30-day and 1-year mortality. American Heart Association (AHA) guidelines for treatment of ACO recommend that the first medical contact to device time be less than 120 minutes in patients who have no contraindications to treatment.2 Though cardiac biomarkers are helpful in making the diagnosis in uncertain cases, the time sensitive nature of intervention for ACO precludes their use to direct emergent reperfusion therapy. Furthermore, biomarkers do not diagnose ACO but rather any AMI, including those without occlusion that do not need emergent intervention.